It is proposed to produce in rhesus monkeys systemic cardiovascular changes which should resemble those seen in the vast majority of the patients with ocular thromboembolic and ischemic disorders. i.e., having atherosclerosis, arterial hypertension, high serum lipids and possibly platelet abnormalities associated with cardiovascular disorders. The long-term goal is to study the pathogenesis, management and other aspects of ocular thromboembolic disorders by experimental occlusion of various ocular vessels in atherosclerotic and hypertensive animals. The monkeys are fed a special high cholesterol synthetic diet. Other animals will have renal hypertension produced. Another group of female monkeys will have high doses of contraceptives. In addition to cardiovascular and hematologic evaluation, detailed examination of their fundus of the eye will be performed.